JP2003507202A - Apparatus and method for Z-axis control and collision detection and recovery for water jet cutting systems - Google Patents

Abstract

SUMMARY The present invention relates to an apparatus and method for Z-axis control and collision detection and recovery for water jet and abrasive jet cutting systems. In one embodiment, the apparatus includes a straight rail, a slide member slidably connected to the cutting head, slidably connected to the straight rail, and a first end connected to the slide member and fixed to the straight rail. At least one actuator having a defined second end, a position sensor, and a controller are included. The actuator provides an adjustable support force to support the weight of the cutting head so that the cutting head is controllably positioned at a desired height above the workpiece. The actuator may comprise a pneumatic cylinder or alternatively comprise a linear motor. In another aspect, an apparatus includes a first mounting member connectable to a controllably positionable mounting surface of a water jet cutting system, and a first head member connectable to a cutting head and disengageably connected to the first mounting member. A second mounting member, and a sensing circuit having a plurality of first conductive elements disposed on the first mounting member and a plurality of second conductive elements disposed on the second mounting member. include. In the event that the cutting head collides with an obstacle, the second mounting member is disengaged from the first mounting member to prevent breakage of the cutting head. Following a collision, the second mounting member re-engages with the first mounting member quickly and easily without time consuming recalibration. In some embodiments, re-engagement of the second and first attachment members is performed automatically by a biasing member.

Description

Detailed Description of the Invention

FIELD OF THE INVENTION The present invention relates to apparatus and methods for Z-axis control and collision detection and recovery for water jet and abrasive jet cutting systems.

BACKGROUND OF THE INVENTION Water jet and abrasive jet cutting systems are used to cut a wide variety of materials. In a typical water jet cutting system, a high pressure fluid (eg, water) flows through a cutting head that has a cutting nozzle that directs the cutting jet onto a workpiece. The cutting nozzle may include a mixing tube for introducing abrasive material into the high pressure cutting jet to form the abrasive cutting jet. The cutting nozzle is controllably moved across the workpiece to cut the workpiece into the desired shape. After the cutting jet (or abrasive cutting jet) has passed through the workpiece, the energy of the cutting jet is dissipated and the fluid is collected in a catch tank and discarded. This type of water jet and abrasive jet cutting system
See, for example, US Pat. No. 5,643,058, granted to Ericsson et al. And assigned to Flow International, Inc. of Kent, Washington, which is incorporated herein by reference. The '058 patent is compatible with Flow International's Pacer 3 abrasive cutting system.

FIG. 1 is a perspective view of a water jet cutting system 10 according to the prior art. The water jet cutting system 10 has a cutting head 20 coupled to a mounting assembly 30. The mounting assembly 30 is a work piece 1.
A control gantry 40 having a drive assembly 42 controllably positioning the cutting head 20 across an xy plane substantially parallel to the two surfaces 14. Drive assembly 42 typically includes a pair of ball screw drives oriented along the x and y axes and a pair of electric drive motors. Alternatively, drive assembly 42 may include a 5-axis actuation system.
Two-axis and five-axis controlled gantry are available from Flow International, Inc. of Kent, WA as Bengal 4x4 cutting system.

FIG. 2 is a partial side view of the cutting head 20 and mounting assembly 30 of the water jet cutting system 100 of FIG. The cutting head 20 has a high-pressure pipe 23.
High pressure fluid inlet 22 connected to a high pressure fluid source 50 such as a high pressure or ultra high pressure pump at
have. In this embodiment, the cutting head 20 includes a nozzle body 24 and a mixing tube 26 terminating in a jet outlet 28. Generally, the term "mixing tube" is used to refer to the portion of the cutting head of an abrasive jet cutting system in which abrasive is mixed with a high pressure fluid jet to form an abrasive cutting jet, but in the discussion that follows "mixing tube" is used. "Tube" is used to refer to the portion of the cutting head 20 closest to the workpiece 12 regardless of whether the water jet cutting system uses an abrasive cutting jet or a non-abrasive cutting jet.

The mounting assembly 30 has a mounting arm 32, through which a mounting opening 34 extends. The mounting arm 32 is connected to the bottom 44 of the control gantry 40. The nozzle body 24 of the cutting head 20 is fixed in the mounting opening 34 of the mounting arm 32.

In operation, high pressure fluid from a high pressure fluid source 50 enters the high pressure fluid inlet 22 through nozzle body 24 and mixing tube 26 and exits from jet outlet 28 toward workpiece 12 as cutting jet 16. . The cutting jet 16 pierces the workpiece 12 to make the desired cut. The control gantry 40 can be used to move the cutting head 20 across the workpiece 12 in a desired direction or pattern.

To maximize cutting efficiency and quality, the separation distance d (FIG. 2) between the jet outlet 28 of the mixing tube 26 and the workpiece 12 surface 14 must be carefully controlled. If the separation distance d is too close, the mixing tube 26 may become stuck during puncture, shutting down the system and damaging the workpiece. If they are too far apart, the quality and accuracy of the cut will be compromised.

The mixing tube 26 is typically made of a special wear resistant tungsten carbide to reduce wear. Particularly in abrasive cutting systems, the mixing tube 26 experiences extreme wear because it is in constant contact with the high speed abrasive. Therefore, the mixing tube is a relatively expensive part of the cutting head 20. This special tungsten carbide is extremely brittle and, during operation of the cutting system 10, if the mixing tube 26 collides with fixtures or obstacles, such as the cutting pieces of the workpiece 12 that were kicked up during the cutting operation, May be easily damaged. Accidental breakage of mixing tube 26 increases operating costs of cutting system 10 and increases downtime.

Current collision sensors use a ring sensor that is placed around the mixing tube 26 and slides along the surface 14 of the workpiece 12 or slightly above it. The ring sensor indicates the relative height of the workpiece. A motorized ball screw moves the cutting head up and down to maintain the required separation. When the ring collides with a raised portion or some obstacle, the detector detects the collision and sends a stop signal to the control gantry, which stops the movement to avoid collision of the mixing tubes.

The basic problem with such a collision sensor is that a “safety buffer” between the sensor and the mixing tube is provided so that the control gantry can be stopped with sufficient time to avoid damage to the mixing tube. Is to be large enough. Due to the size and speed of modern cutting systems, it is extremely difficult to quickly stop the control gantry to avoid collisions. Another problem is that offsetting the components requires a very long recalibration routine to ensure proper separation d. If the collision is severe, the ring sensor may be damaged.

One remedy was to simply increase the size of the ring to allow the control gantry some room to stop. But this method is
Material is wasted because 6 makes it impossible to cut near obstacles and fixtures that commonly appear around the edges of workpiece 12. Also, larger rings increase the chances of issuing false collision signals that cause unnecessary downtime of the cutting system. Finally, the presence of the ring sensor device itself is a source of cost and loss of robustness in detecting surface height or collisions when operating the control gantry at high speeds or in dusty environments. Becomes

SUMMARY OF THE INVENTION The present invention is directed to an apparatus and method for Z-axis control and collision detection and recovery for water jet and abrasive jet cutting systems. In one aspect of the invention, the device comprises a linear rail, a sliding member connectable to the cutting head and slidably connected to the linear rail, a first end connected to the sliding member and the linear rail. There is at least one actuator having a fixed second end, a position sensor coupled to the sliding member, and a controller. The actuator provides an adjustable bearing force to support the weight of the cutting head, allowing the cutting head to be controllably positioned at a desired height above the workpiece. The actuator is
It is equipped with a pneumatic cylinder, or a linear motor instead.

In another aspect, an apparatus according to the invention includes a first attachment member connectable to a controllably positionable attachment surface of a water jet cutting system and a cutting head connectable to the first attachment member. Sensing having a second attachment member releasably coupled, a plurality of first electrically conductive elements arranged on the first attachment member and a plurality of second electrically conductive elements arranged on the second attachment member. It has a circuit.
If the cutting head and the obstacle collide with each other, the second mounting member is disengaged from the first mounting member to prevent the cutting head from being damaged. Following the collision, the second mounting member reengages with the first mounting member quickly and easily without time consuming recalibration. In some embodiments, the re-engagement of the second and first attachment members is done automatically by the biasing member.

In yet another aspect, a method of controlling the height of a cutting head of a water jet cutting system on a surface of a workpiece includes a step of connecting a first end of a contact member to the cutting head and a contacting step. Engaging the second end of the member with the surface of the workpiece, providing an adjustable and controllable support force to support the weight of the cutting head, and biasing the contact member slightly downwardly. And slightly reducing the supporting force to engage the surface of the workpiece. The position control method conveniently provides a simple height measurement system and can automatically adjust for changes in friction and weight of various components of the water jet cutting system.

Detailed Description of the Preferred Embodiments The present disclosure is directed to apparatus and methods for Z-axis control and collision detection and recovery of a cutting head of a waterjet cutting system. Although specific details regarding certain embodiments of the invention are described below, a general understanding of such embodiments may be obtained with reference to FIGS. 3-9. However, one of ordinary skill in the art will appreciate that alternative embodiments of the present invention are contemplated and that the present invention may be practiced without some of the details described below.

FIG. 3 is a perspective view of a water jet cutting system 100 according to an embodiment of the present invention. Water jet cutting system 100 includes a cutting head 120 coupled to a disengageable (ie, separable) mounting assembly 160. In the event of a collision, the disengageable mounting assembly conveniently disengages (or separates) to prevent damage to the mixing tube 26 or other cutting head components. After a collision occurs and the water jet cutting system 100 shuts down, the disengageable mounting assembly 160 is easily re-engaged and the cutting operation can continue without the need for a lengthy recalibration procedure.

The water jet cutting system 100 also includes a high pressure fluid source 50 fluidly coupled to the cutting head 120 by a coiled high pressure line 123. The disengageable attachment system 160 is attached to the attachment arm 132, which is connected to the control gantry 40 previously described. The high pressure fluid source 50 is
For example, it may be a high pressure pump or an ultra high pressure pump such as the Husky pump model available from Flow International, Inc. of Kent, Washington.

FIG. 4 is a partial cross-sectional side view of the cutting head 120 and disengageable mounting assembly 160 of the water jet cutting system 100 of FIG. 5 is an exploded perspective view of the disengageable mounting assembly 160 of FIG. As shown in FIG. 4, the cutting head 120 includes a high pressure fluid inlet 22, which is connected to the coiled high pressure pipe 123, a nozzle body 24, and a mixing tube 26. The mixing tube 26 includes a jet outlet 28 from which a cutting jet 16 is fired toward the workpiece 12. A collision shield 127 is provided around the mixing tube 26 to protect the mixing tube 26 from collisions. The collision shield 127 has a wear ring 129.
Is included. As described in detail below, the water jet cutting system 100
In some of the modes of operation, the wear ring 129 engages the surface 14 of the workpiece 12 and in others, the wear ring 129 is positioned slightly above the surface 14. The wear ring 129 may be made of the same material as the collision shield 127, or it may be made of a low friction material such as Teflon. The impingement shield 127 has a length 1 dimensioned to provide a constant desired separation distance d between the jet outlet 28 and the surface 14.

The disengageable mounting assembly 160 includes a top surface 1 of the mounting arm 132.
It includes a retainer 162 attached to 33. A large mounting opening 134 is provided through the mounting arm 132. The retainer 162 has a seating opening 1 aligned with the large mounting opening 134 of the mounting arm 132.
Includes 64. As best seen in FIG. 5, retainer 162 further includes three pin cavities 166 disposed around the circumference of seating opening 164. Each pin cavity 166 is provided with a pair of round pockets 168 on opposite sides of each cavity. A conductive strike pad 17 is located at the bottom of each circular pocket 168.
0 is placed. Similarly, a conductive ball 172 is disposed within each circular pocket 168 in contact with the associated strike pad 170.

The clamp collar 174 is attached to the nozzle body 24 of the cutting head 120, a part of which is located in the seating opening 164. Three conductive pins 176 project from the clamp collar 174. The clamp collar 174 has a seating opening 16
When seated in the seat 4, the conductive pin 176 projects into the pin cavity 166 and contacts the conductive ball 172. The disengageable mounting assembly 160 includes a seating force spring 178 disposed around the nozzle body 24 and engaging the lower surface 135 of the mounting arm 132. The tensioner 179 engages the nozzle body 24 (eg, by screw engagement) and partially compresses the seating force spring 178. Collision sensing circuit 180
Are formed on retainer 162, which will be described in more detail below.

FIG. 6 illustrates a collision sensing circuit 18 of the disengageable mounting assembly 160 of FIG.
FIG. Collision sensing circuit 180 includes a plurality of conductive elements 182 coupled in parallel to strike pad 170 and resistor 184. The voltage source 186 is electrically coupled to the resistor 184. The strike pad 170 is in electrical contact with a conductive ball 172, which is connected to the ground 188 by another conductive element 182. Each resistor 184, strike pad 170
, And the conductive balls 172 form one branch line in the parallel circuit. The secondary conductive element 189 includes a collision controller 190, a resistor 24 and a strike pad 17.
It is electrically connected to the conductive element 182 between zero. The collision controller 190 sends a first collision detection signal 192 to the high pressure fluid source 50. Collision controller 1
90 also sends a second crash detect signal 194 to the control gantry 40 and a third crash detect signal 196 to the Z-axis control assembly 200, which is described in further detail below.

The disengageable mounting assembly 160 shown in FIGS.
Known as a clamp. The Kelvin Clamp is a coordinate measuring instrument (CMM) sold by Renishaw PLC, Inc., Gloucestershire, UK, which is introduced and described on touch probes and other precision measuring instruments such as www.renishaw.uk.com. )
It has been adopted in.

In operation, the disengageable mounting assembly 160 prevents breakage of the mixing tube 26 by disengaging in the event of a collision. The wear ring 129 moves across the surface 14 as the control gantry 40 moves the cutting head 120 in an xy plane substantially parallel to the surface 14 of the workpiece 12. In this embodiment, the collision shield 12
7 is provided around the mixing pipe 26. When the collision shield 127 hits an obstacle, the force of the collision exerts a torque on the nozzle body 24 of the cutting head 120. The nozzle body 24 begins to rock within the large mounting opening 134 of the mounting arm 132, causing the clamp collar 174 to rotate within the seating opening 164. The impact force required to pivot the nozzle body 24 is determined by the amount of compressive force on the seating force spring 178, which can be adjusted by adjusting the position of the tensioner 179.

As the clamp collar 174 rotates, the one or more conductive pins 176 are disengaged from the associated conductive balls 172, thereby causing one or more branches of the collision sensing circuit 180 to disengage. The line circuit is disconnected. Collision controller 19
0 monitors the branch line of the collision sensing circuit 180 via the second conductive lead 189,
Detect the occurrence of collision. The collision controller 190 then sends a first collision detection signal 192 to the high pressure fluid source 50 to block the flow of high pressure fluid through the cutting head 160. The collision controller 190 also sends a second collision detection signal 194 to the control gantry 40 to stop the movement of the cutting head 160. Finally, the collision controller 190 sends a third collision detection signal 196 to the Z-axis control system 200. In addition to this, in the polishing jet cutting system, the collision controller 190 will also send a fourth collision detection signal to shut off the flow of abrasive material to the cutting head 120.

After the water jet cutting system 100 has been shut down by the collision controller 190, the collision shield 127 is released from the obstruction and the disengageable mounting assembly 160 reseals the clamp collar 174 into the seating opening 164. And is simply re-engaged by reseating conductive pin 176 within pin cavity 166. In this embodiment, the clamp collar 174 automatically reseats within the seating opening 164 under the force of the seating force spring 178. In another embodiment, the clamp collar 174 is manually reseated into the seating opening 164. Conductive pin 17
After 6 is reseated, the branch of sensing circuit 180 is reestablished. Cutting head 120
When is repositioned by the control gantry 40, the cutting operation is restarted quickly and easily.

The disengageable mounting assembly 160 provides the cutting head 120 with a collision.
It is useful in preventing damage to the mixing tube 26 and other components. When a collision occurs, the cutting head 120 simply moves off axis. At the same time, a collision detection signal is generated, which automatically shuts down the various subsystems. The disengageable mounting assembly 160 allows the cutting head 120 to return to its pre-impact condition with good repeatability, maintaining machine calibration and restarting cutting without the user having to perform a readjustment operation. You can do it. Following the collision, the mounting assembly 1
The 60 is quickly re-engaged and the disconnection operation restarted without recalibration or other time consuming procedure.

The disengageable mounting assembly 160, shown above in the drawings and described as a Kelvin clamp in the previous discussion, serves the function of pivoting the cutting head 120 off axis in the event of a collision. It will be appreciated that other disengageable mounting assemblies capable of Thus, while prior art collision sensing systems have focused on attempting to avoid collisions, the disengageable mounting assembly allows the apparatus and method of the present invention to recognize that collisions are unavoidable. Accepting the collision.

FIG. 7 is a partially exploded rear perspective view of the water jet cutting system 100 of FIG. As shown in this figure, the water jet cutting system 100 includes a Z-axis control system 200 disposed within a housing portion 202. Back plate 2
04 is connected to a pair of guide blocks 206 in order to seal the rear side portion of the housing part 202, and is connected to the control gantry 40. Thus, the Z-axis control system 200, along with the cutting head 120, is controllably positioned by the control gantry 40.

The Z-axis control system 200 further includes a pair of air cylinders 208, each air cylinder fixedly attached to the housing portion 202 at a first end 210.
The second end 212 is attached to the sliding member 214. The mounting arm 132 is mounted on the sliding member 214. The linear rail 216 is connected to the sliding member 214 and is arranged between the air cylinders 208. The linear rails 216 are slidably engaged with the pair of guide blocks 206. The air brake 218 is attached to the sliding member 214 and is slidably engaged with the linear rail 216. The air cylinder 208 and the air brake 218 are fluidly connected to a high pressure air source 220. The first air control valve 222 controls the flow from the high pressure air source 220 to the air cylinder 208, and the second air control valve 223 controls the air flow to the air brake 218. The air brake 218 is a "pressurize required" pneumatic brake that keeps the sliding member 214 in place when the air pressure drops and prevents the sliding member 214 (and the cutting head 120) from falling. It is desirable to have.

The position sensor 224 is provided on the sliding member 214 and the second end 2 of both air cylinders 208.
It is attached between 12 members. In this embodiment, the position sensor 224 is
It includes a cable 226 attached to the upper guide block 206.
One of the commercially available position sensors suitable for this purpose is the LX-PA-15 string potentiometer sold by Unimajer Corp. of Corvallis, Oregon. The Z-axis controller 230 includes a position sensor 224, a first
And the second air control valves 222, 223 and the collision controller 190 are electrically connected.

In operation, the Z-axis control system 200 supports the weight of the cutting head 120 and controls the air pressure in the air cylinder 208 to quickly raise and lower the cutting head 120. As such, the air cylinder 208 provides a constant upward biasing force to support the weight of the cutting head 120 and reduces the tracing force of the collision shield 127 on the workpiece 12. If a collision is detected by the collision controller 190,
The collision controller 190 outputs the third collision detection signal 196 to the Z-axis controller 230.
Send to. The Z-axis controller 230 sends a brake control signal 231 to the second air control valve 223 to release the air brake 218.
32 to the first air control valve 222 to increase the air pressure in the air cylinder 208,
Lift the sliding member 214. It should be understood that the functions of Z-axis controller 230 and collision controller 190 may be combined into a single controller.

As the sliding member 214 rises, the cable 226 is withdrawn from the position sensor 224. The position sensor 224 causes the cable 22 to move when the sliding member 214 moves.
6 determines the extracted amount and sends a position signal 228 to the Z-axis controller 230. In response to the position signal 228, the Z-axis controller 230 causes the air control signal 232.
To the air control valve 222 to raise and lower the air pressure in the air cylinder 208.

It should be appreciated that the actuators of the Z-axis control system 200 may differ from the particular embodiment shown in FIG. 7 and described above. For example, one air cylinder may be adopted instead of the pair of air cylinders 208. Alternatively, one or more of the air cylinders 208 can be replaced with a linear motor. Commercially available motors suitable for this purpose include, for example, those sold by Trilogy Systems, Inc. of Webster, Texas. However, generally speaking, the air cylinder 208 is less expensive than other actuators. Commercially available air cylinders suitable for this purpose include, for example, the Airpel 16mm air cylinder sold by Airport Corporation of Norwalk, Connecticut.

One of the advantages of the Z-axis control system 200 is that it enables a unique mode of operation of the water jet cutting system 100, which mode is referred to herein as "biased follow." . Using a biased tracking scheme, the cutting head 120 will engage the surface 14 of the workpiece 12. Therefore, the workpiece 12
The height of can be easily measured by measuring the position of the cutting head 12. However, without the Z-axis control system 230, the relatively heavy cutting head 120 would create an excessive and unacceptable load on the workpiece 12, precluding the use of a biased tracking scheme. The Z-axis control system 200 is
Advantageously, it provides a constant upward biasing force that can accommodate some or all of the path to the cutting head 120, which significantly reduces or eliminates tracing forces on the workpiece 12 and biased tracking. Will be able to use the method of successfully.

Another advantage of the Z-axis control system 200 is that the cutting head 120 can be lifted quickly. Prior art ball screw drive systems are typically capable of raising or lowering the cutting head at a speed of about 40 cm / min. With a linear actuator, the Z-axis control system 200 allows the cutting head to move about 40 cm.
It becomes possible to raise or lower at a speed of / second. Thus, the Z-axis control system of the present invention is about 60 times faster than prior art drive systems.

The Z-axis control system 200 has five basic modes of operation: 1) biased tracking (or height sensing) cutting mode, 2) set high cutting mode, 3) manual up / down mode, 4 ) Park mode and 5) Calibration mode. The calibration mode is used to test the performance of the Z-axis control system 200 or initially set up the system. Simply put, the pressure in the air cylinder can be varied until a neutral pressure is found. Neutral pressure is the pressure at which cutting head 120, sliding member 214 and other components (collectively referred to as the "shaft") do not rise or fall when the air brake is released. The upper and lower limits of the "dead zone" of neutral pressure are detected and recorded. Also, the upper and lower limits of the movement amount of the shaft portion are detected and recorded. These data are used to set values for other motion modes, and this "dead zone" data is a diagnostic tool for determining if the shaft is in need of repair due to excessive friction. Used as.

FIG. 8 is a flowchart of a calibration routine 300 for Z-axis control system 200 according to one embodiment of the invention. Initially, the pressure in the air cylinder is set 302 to a default pressure or to a neutral or neutral pressure corresponding to a position where the cutting head does not move. Next, the air brake is released 304. After the air brake is released, it is determined 306 whether the shaft portion is rising. If the shaft is raised,
The pressure in the air cylinder is reduced 308 in increments. The determination 306 of whether the shaft is rising and the operation 308 for reducing the pressure are repeated until the shaft stops rising.

If it is determined 306 that the shank has not risen, then it is determined 310 whether the shank has descended. If the Z-axis is down, the pressure in the air cylinder is increased 312 in increments. The determination 310 and the increment of pressure increase 312 are repeated until the shaft no longer descends.

However, if the default pressure setting 302 is actually a neutral pressure setting, then the steps 306 through 312 are not necessary for the calibration procedure 300. However, if the default pressure setting 302 is not a neutral pressure setting, for example, one or more components of the cutting head have been changed or removed since the last calibration, then 306-312. The above operations are performed to establish an appropriate neutral pressure setting.

As shown in FIG. 8, if it is determined that the shank has not descended, another determination 314 is made whether the shank 314 has not risen. If it is determined that the shank is not elevated, then the pressure is increased in increments 316 and the calibration procedure 300 returns to the shank elevated or undecided 314. Judgment 314 and pressure increase in increments of 3
16 is repeated until the shaft portion is lifted.

If the shaft is elevated 314, the Z-axis controller 318 records the upper threshold pressure. The upper threshold pressure means the pressure in the air cylinder at which the shaft starts to rise.

Next, a determination is made 320 as to whether the shank is descending. If it is determined that the shank has not descended, then the pressure is reduced 322 in increments. Calibration procedure 30
0 now returns to the determination 320 of whether the shank is descending. The determination 320 and the pressure reduction 322 in increments are repeated until the shaft is lowered.

If the shaft is down 320, the Z-axis controller records the lower threshold pressure 324. Lower threshold pressure means the pressure within the air cylinder at which the shaft will begin to move downward.

Next, the air cylinder pressure is increased 326 to an upper threshold value plus an incremental step pressure. Next, a determination is made 328 as to whether the shaft is moving. If the shank is moving, the rate of upward movement of the shank is recorded 330. The determination 328 of whether the shaft is moving and the record 330 of the speed of the upward movement are repeated until the shaft stops moving and the upper limit of the moving amount is reached. When the shaft does not move 328, the upper limit of the movement is recorded 332.

The calibration procedure 300 then reduces 334 the pressure in the air cylinder to the lower threshold minus the incremental stage pressure 334. Next, a determination is made 336 as to whether the shaft is moving. If the shank is moving, the speed of downward movement of the shank is recorded 338. The determination 336 and the downward movement speed recording 338 are repeated until the shaft portion does not move and the lower limit of the movement amount is reached. When the shaft does not move 336, the lower limit of movement is recorded 340. The calibration procedure 300 is
Completed here 342.

In the set high cutting mode, the shaft is manually or automatically moved to a fixed position. When automatically moved into position, the shank moves downward until it engages the surface 14 of the workpiece 12 by lowering the shank until it stops moving, and then, if necessary, the appropriate spacing. Raise to the distance. Z-axis control system 200 assumes neutral pressure with the air brake engaged.

In the manual ascending / descending mode, the shaft is moved until the end of the movement limit is reached by the operator's command, or the wear ring 129 of the collision shield 127 is moved to the workpiece 1.
It is raised or lowered until it contacts the surface 14 of the second. The shaft portion can be raised or lowered by, for example, inputting an ascending or descending movement command to the Z-axis controller 190 with a keyboard (not shown). When you reach the limit of movement, all movement stops. When the move command is removed, or when the end of the move is reached, the shaft receives a counter pressure signal to decelerate itself. The reverse pressure signal is based on, for example, the speed of the shaft. If the shank moves continuously, it seeks a constant speed. Incremental movements are based, for example, on individual keystrokes (or individual mouse clicks, etc.) of the keyboard that move the shaft up or down a predetermined distance. In either incremental or continuous movement, movement is terminated by engaging the air brake.

In the park mode, the shaft is simply lifted to the limit of movement and the air brake is engaged. The pressure in the air cylinder is set to the neutral bias setting.

In the biased follow (or height sensitive) cutting mode, the shank has a slight downward biasing pressure. With a slight downward bias, the shank slowly drops and wear ring 1
A constant contact of 29 with the surface 14 of the workpiece 12 is maintained. Upward stiction is compensated for by rapidly raising and lowering the pressure within the dead zone between the lower and upper threshold pressures. Air brake 218 is not engaged.

FIG. 9 illustrates a biased tracking of a Z-axis control system 200 according to an embodiment of the invention (
Or a height sensing routine 400. In this embodiment, the energized follow routine 400 begins by reducing the pressure in the air cylinder to a lower threshold pressure minus the incremental stage pressure 402. Next, the air brake is released 404. Next, a determination is made whether the shaft is moving 40.
6. If the shaft is moving, the determination 406 is repeated indefinitely until the shaft does not move. If the shank is not moving, the pressure in the air cylinder is varied 408 between an upper threshold pressure and a lower threshold pressure. Next, a determination is made 410 whether a collision has occurred. If no collision has occurred, the collision determination 410 is simply repeated indefinitely. If a collision has occurred, Z-axis control system 200 is interrupted 412. Alternatively, in the event of a collision, the pressure within the air cylinder may be increased and the shank quickly lifted away from the workpiece.

Another advantage of the Z-axis control system 200 is the friction and / or friction of system components such as air cylinders 208, linear rails 216, guide blocks 206, wear components such as bearings, and other system components. It is to automatically compensate for changes in weight. The Z-axis controller 230 maintains the engagement of the wear ring 129 with the surface 14 of the workpiece 12 in the biased follow mode of operation by adjusting the pressure within the air cylinder 208 that causes the sliding member 214 to descend. By or by maintaining the wear ring 129 at a constant height above the surface 14 in the set high mode of operation. In this way, the separation distance d is maintained at a desired value despite changes in friction and / or weight of various system components.

Above, an improved apparatus and method for Z-axis control and collision recovery of a cutting head of a water jet cutting system has been shown and described. Although the embodiments of the present invention have been described above for the purpose of explanation, it will be understood that various changes can be made without departing from the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described herein, but is defined by the subject matter of the claims.

[Brief description of drawings]

[Figure 1]   1 is a perspective view of a water jet cutting system according to the prior art.

2 is a partial side view of the cutting head and mounting assembly of the water jet cutting system of FIG. 1. FIG.

FIG. 3 is a front perspective view of a waterjet cutting system according to one embodiment of the invention.

FIG. 4 is a partial side view of the cutting head and disengageable mounting assembly of the water jet cutting system of FIG.

[Figure 5]   FIG. 5 is an exploded perspective view of the disengageable mounting assembly of FIG. 4.

[Figure 6]   FIG. 6 is a schematic diagram of a collision sensing circuit of the disengageable mounting assembly of FIG. 5.

[Figure 7]   FIG. 4 is a partially exploded rear perspective view of the water jet cutting system of FIG. 3.

FIG. 8A is a flow chart of a calibration routine for a Z-axis control system according to an embodiment of the invention.

FIG. 8B is a flowchart of a calibration routine for a Z-axis control system according to one embodiment of the invention.

FIG. 9 is a flowchart of a biased tracking routine for a Z-axis control system according to one embodiment of the invention.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, MZ, SD, SL, SZ, TZ, UG , ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, BZ, C A, CH, CN, CR, CU, CZ, DE, DK, DM , DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, K E, KG, KP, KR, KZ, LC, LK, LR, LS , LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, R U, SD, SE, SG, SI, SK, SL, TJ, TM , TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW (72) Inventor Pesec Thomas             Germany Day 64347 Grease             Heim am schwinbert 16 (72) Inventor Cologne Volker             Federal Republic of Germany Day 55270 Zornha             Im Neugasse 15 (72) Inventor Wu Cheng Chou             Taiwan Shinchu Science Base             Do Industrial Park Technoro             G 3rd Road # 2 (72) Inventor Chin Daniel             Washington, United States 98118             Seattle four nines avenue             -South 6611 (72) Inventor Siuri Ferris M             Washington, United States 98029             Ithaca Two Hundred and Toe             Entity Sixth Avenue South             East 2712 F term (reference) 3C060 AA20 CE08 [Continued summary] A sensing circuit is included. Should the cutting head and obstacles The second mounting member, the first mounting portion Disengaged from the material to prevent damage to the cutting head. Opposition Following the bump, the second mounting member can be quickly and easily The first mounting member without re-calibration which consumes Re-engage. In some embodiments, the second and first attachments Re-engagement of the members is done automatically by the biasing member.

Claims (67)

[Claims] 1. A water jet cutting system for cutting a workpiece, a high pressure fluid inlet connectable to a high pressure source, an orifice for producing a cutting jet, and a mixing tube positionable above the workpiece. A cutting head having a linear rail extending outward with respect to the workpiece, a sliding member connected to the cutting head and slidably connected to the linear rail, and connected to the sliding member. A first end and a second fixed to the straight rail
At least one actuator having an end, a position sensor coupled to the sliding member, operatively coupled to the position sensor and the actuator, receiving a position signal from the position sensor, and controlling the actuator A water jet cutting system, comprising: a controller that transmits a signal. 2. The actuator comprises a pneumatic cylinder having an air valve connectable to a high pressure air source, and the controller is operably connected to the air valve. Water jet cutting system according to. 3. The water jet cutting system according to claim 2, further comprising a high pressure air source connected to the air valve. 4. The contact member according to claim 1, further comprising a contact member having a first end attached to the cutting head and a second end engageable with a surface of the workpiece. The described water jet cutting system. 5. The position sensor of claim 1, wherein the position sensor comprises a potentiometer including a spring-loaded string having a free end fixed to the linear rail. Water jet cutting system. 6. The actuator includes a first pneumatic cylinder having a first air valve connectable to a high pressure air source, and a second pneumatic cylinder having a second air valve connectable to the high pressure air source. The method of claim 1, further comprising: the controller operably coupled to the second air valve and sending a second control signal to control the second air valve. Water jet cutting system. 7. The water jet cutting system according to claim 1, further comprising a high pressure fluid source. 8. The water jet cutting system according to claim 7, wherein the high pressure fluid source comprises a high pressure pump. 9. The control gantry according to claim 1, further comprising a control gantry having a drive assembly for controllably positioning the cutting head on an xy plane substantially parallel to a surface of the workpiece. Water jet cutting system according to. 10. The water jet cutting system according to claim 9, wherein the control gantry comprises a two-axis control gantry. 11. A position control device for a cutting head of a water jet cutting system, wherein a linear rail arranged to extend outwardly with respect to a workpiece and a linear rail connectable to the cutting head. At least one actuator having a sliding member slidably connected, a first end connected to the sliding member, and a second end fixed to the linear rail; A position sensor connected thereto, and a controller operatively connected to the position sensor and the actuator, receiving a position signal from the position sensor, and transmitting a control signal to the actuator. Position control device. 12. The actuator comprises a pneumatic cylinder having an air valve connectable to a high pressure air source and the controller is operatively connected to the air valve. 11. The position control device according to item 11. 13. The position control device according to claim 12, further comprising a high pressure air source connected to the air valve. 14. The contact member of claim 11, further comprising a contact member having a first end attachable to the cutting head and a second end engageable with a surface of the workpiece. Position control device. 15. The position sensor of claim 11, wherein the position sensor comprises a potentiometer including a spring loaded string having a free end fixed to the linear rail. Position control device. 16. The actuator comprises a first pneumatic cylinder connectable to an air valve connected to a high pressure air source, and further comprises a second pneumatic cylinder connectable to the air valve, wherein the controller comprises: The position control device according to claim 11, wherein the position control device is operatively connected to the air valve and sends a control signal to the air valve. 17. The position control device according to claim 11, further comprising a mounting arm and a brake connected to the linear rail. 18. The brake according to claim 17, further comprising an air brake connected to the controller and connectable to a high pressure air source.
The position control device according to. 19. The position control device according to claim 18, wherein the air brake is released when a large amount of high-pressure air is supplied to the air brake. 20. A disengageable mounting assembly for a cutting head of a water jet cutting system, the retainer mountable on a top surface of a mounting arm of the water jet cutting system, the retainer having a seating opening in the retainer. A plurality of pin cavities are provided, each pin cavity being a retainer having a pair of pockets disposed on opposite sides thereof, and a plurality of pairs of conductive strike pads, each strike pad being A conductive strike pad disposed in one of the pockets and a plurality of pairs of conductive balls, each conductive ball disposed in one of the pockets and in contact with one of the strike pads. A conductive ball that is connectable to the cutting head and is at least partially within the seating opening. A clamp collar disposed therein, the clamp collar having a plurality of outwardly projecting conductive pins, each conductive pin releasably disposed within one of the pin cavities. And a clamp collar, which is in disengageable contact with the pair of conductive balls, a seating force spring engageable with the lower surface, a seating force connectable with the cutting head, and at least partially the seating force. A tensioner engageable with the seating force spring for compressing a spring, and a sensing circuit attached to the retainer, the sensing circuit having a plurality of sensing branches, each sensing branch comprising at least one of the strike pads. A disengageable mounting assembly comprising one and at least one sensing circuit operatively coupled to one of the conductive balls. 21. The engagement of claim 20, wherein the plurality of pin cavities are comprised of three pin cavities and the plurality of conductive pins are comprised of three conductive pins. Releasable mounting assembly. 22. The disengageable mounting assembly according to claim 20, wherein the seating force spring comprises a coil spring that is substantially aligned with the mounting opening. 23. The disengageable mounting assembly according to claim 20, wherein the seating opening is substantially alignable with the mounting opening of the mounting arm. 24. The assembly of claim 20, further comprising a shield member having a first end attachable to the cutting head and a second end engageable with the workpiece. Detachable mounting assembly. 25. The disengageable mounting assembly according to claim 20, further comprising a controller operably coupled to the sensing circuit. 26. The disengageable mounting assembly according to claim 25, wherein the controller sends a collision detection signal to a control gantry of the water jet cutting system. 27. A disengageable mounting assembly for a cutting head of a water jet cutting system, the first mounting member being connectable to a controllably positionable mounting surface of the water jet cutting system, and the cutting head. A second mounting member that is connectable to the first mounting member and is disengageably coupled to the first mounting member; a plurality of first conductive elements disposed on the first mounting member;
A sensing circuit having a plurality of second conductive elements disposed on the mounting member;
And a disengageable mounting assembly. 28. The first attachment member comprises a retainer, the retainer having a seating opening extending therethrough, and a plurality of pin cavities disposed therein.
The pin cavities each have a pair of round pockets disposed on opposite sides thereof, the plurality of first conductive elements having conductive strike pads disposed in each of the pockets, and A conductive ball disposed in contact with the strike pad in each of the pockets,
28. The disengageable mounting assembly according to claim 27. 29. The second attachment member comprises a clamp collar disposed at least partially within the seating opening, the plurality of second conductive elements projecting outwardly from the clamp collar. Is equipped with multiple conductive pins,
29. The engagement of claim 28, wherein each conductive pin is releasably disposed in one of the pin cavities and is in releasable contact with a pair of conductive balls. Detachable mounting assembly. 30. The disengageable mount of claim 27, further comprising a biasing device that biases the second mounting member into contact with the first mounting member. assembly. 31. The disengageable mounting assembly according to claim 30, wherein the biasing device comprises a coil spring. 32. The separable mounting assembly of claim 27, further comprising a controller operably coupled to the sensing circuit and monitoring a collision sensing signal. 33. A water jet cutting system for cutting a workpiece, a cutting head having a high pressure fluid inlet connectable to a source of high pressure fluid and a first mounting member connectable to a controllably positionable mounting surface. A second mounting member connected to the cutting head and releasably connected to the first mounting member; a plurality of first conductive elements disposed on the first mounting member; The second
A sensing circuit having a plurality of second electrically conductive elements disposed on the mounting member. 34. The first mounting member comprises a retainer, wherein the retainer has a seating opening extending therethrough and a plurality of pin cavities disposed therein.
The pin cavities each have a pair of round pockets disposed on opposite sides thereof, the plurality of first conductive elements having conductive strike pads disposed in each of the pockets, and A conductive ball disposed in contact with the strike pad in each of the pockets,
A water jet cutting system according to claim 33. 35. The second mounting member comprises a clamp collar disposed at least partially within the seating opening, the plurality of second conductive elements projecting outwardly from the clamp collar. Is equipped with multiple conductive pins,
35. The water of claim 34, wherein each conductive pin is releasably disposed in one of the pin cavities and is in releasable contact with a pair of conductive balls. Jet cutting system. 36. A biasing device engageable with the cutting head and the mounting surface for biasing the second mounting member into contact with the first mounting member. 34. The water jet cutting system according to claim 33. 37. The water jet cutting system of claim 33, further comprising a controller operably coupled to the sensing circuit and monitoring a collision sensing signal. 38. A control gantry further comprising a drive assembly coupled to the mounting surface and controllably positioning the cutting head through an xy plane substantially parallel to a surface of the workpiece. 34. Characteristic, 33.
Water jet cutting system according to. 39. The high pressure fluid source of claim 3, further comprising:
The water jet cutting system according to item 3. 40. A linear rail alignable with an axis extending outward relative to the workpiece, a sliding member coupled to the mounting surface and slidably coupled to the linear rail, and the sliding member. A first end connected to the second rail and a second end fixed to the straight rail.
At least one actuator aligned with the linear rail having an end; a position sensor connected to the sliding member; and a position signal operatively connected to the position sensor and the actuator. 34. The water jet cutting system of claim 33, further comprising: a controller that receives the control signal and transmits a control signal to the actuator. 41. The actuator of claim 40, wherein the actuator comprises a pneumatic cylinder having an air valve connectable to a high pressure air source, and the controller is operably connected to the air valve. Water jet cutting system according to. 42. The water jet cutting system of claim 41, further comprising a high pressure air source connected to the air valve. 43. The method of claim 40, further comprising a contact member having a first end attached to the cutting head and a second end engageable with a surface of the workpiece. Water jet cutting system. 44. The actuator comprises a first pneumatic cylinder having a first air valve connectable to a high pressure air source, and a second pneumatic cylinder having a second air valve connectable to the high pressure air source. 41. The apparatus of claim 40, further comprising, wherein the controller is operably connected to the second air valve and sends a second control signal to control the second air valve. Water jet cutting system. 45. A method of collision detection and recovery for a cutting head of a water jet cutting system, the step of mounting the cutting head on a disengageable mounting assembly having a collision sensing circuit, the method comprising: Of the collision detection signal, the step of colliding the cutting head with a foreign object, the step of disengaging the disengageable mounting assembly, and the step of confirming that a collision has occurred from the collision detection signal And sending a stop signal to the water jet cutting system. 46. The method of claim 45, further comprising the step of disengaging the cutting head from the foreign object. 47. The method of claim 45, further comprising sending an actuation signal to a Z-axis control system attached to the cutting head. 48. The method of claim 45, further comprising the step of re-engaging the disengageable mounting assembly. 49. The method of claim 45, wherein the step of sending a stop signal to the water jet cutting system comprises sending a deadline signal to a high pressure fluid source of the water jet cutting system. The method described. 50. A method of controlling the height of a cutting head of a water jet cutting system on a surface of a workpiece, the method comprising: connecting a first end of a contact member to the cutting head; Engaging an end with the surface of the workpiece, providing an adjustable and controllable support force to support the weight of the cutting head, and biasing the contact member slightly downwardly. Slightly reducing the bearing force to engage the surface of the workpiece. 51. The method of claim 50, wherein the step of providing an adjustably controllable bearing force comprises the step of adjustably pressurizing an air cylinder connected to the cutting head. the method of. 52. The step of slightly reducing the support force to bias the contact member slightly downward includes the step of slightly reducing the air pressure in an air cylinder connected to the cutting head. 51. The method of claim 50, wherein: 53. The method of claim 50, further comprising: monitoring a collision detection signal; and transmitting a control signal in response to the collision detection signal. 54. The method of claim 53, wherein the step of sending a control signal in response to the collision detection signal comprises sending a stop signal to a control gantry of the water jet cutting system. The method described. 55. The step of transmitting a control signal in response to the collision detection signal includes the step of transmitting a control signal to an air flow control valve to increase air pressure in an air cylinder connected to the cutting head. 54. The method of claim 53, including. 56. The method further comprising the step of periodically adjusting the adjustable support force without changing the height of the cutting head.
The method described in. 57. A method of calibrating a height control system of a cutting assembly including a cutting head of a water jet cutting system on a surface of a workpiece, the method being adjustably controllable to support the weight of the cutting assembly. Different supporting forces, setting a supporting force that is approximately equal to the weight of the cutting assembly, checking whether the cutting assembly is moving away from the workpiece, and setting an upper threshold of the supporting force. Recording, confirming whether the cutting assembly is moving towards the workpiece, recording a lower threshold of the bearing force, and adding the bearing force to an upper threshold of the bearing force plus The steps of setting the supporting force increment step and the speed at which the cutting assembly moves away from the workpiece are noted. And a step of confirming whether the cutting assembly is moving away from the workpiece, recording an upper limit of the movement of the cutting assembly, the supporting force, the lower threshold of the supporting force minus the Setting an incremental step of the supporting force, recording the speed at which the cutting assembly approaches the workpiece, checking whether the cutting assembly is facing the workpiece, the cutting Recording a lower limit of movement of the assembly. 58. The step of providing an adjustably controllable support force to support the weight of the cutting assembly provides an adjustably controllable pneumatic pressure in an air cylinder coupled to the cutting assembly. 58. The method of claim 57, including the step of: 59. The method of claim 57, wherein the step of setting a bearing force approximately equal to the weight of the cutting assembly includes the step of setting the pressure in the air cylinder to a default pressure value. Method. 60. The step of establishing a bearing force approximately equal to the weight of the cutting assembly includes the step of determining if the cutting assembly is moving toward the workpiece. Item 57. The method according to Item 57. 61. The method of claim 60, further comprising the step of reducing the bearing force by an incremental process force. 62. The step of establishing a bearing force approximately equal to the weight of the cutting assembly includes the step of determining if the cutting assembly is moving away from the workpiece. The method of claim 57. 63. The method of claim 62, further comprising increasing the bearing force by an incremental process force. 64. The method of claim 57, further comprising increasing the bearing force by an incremental step force. 65. The method of claim 64, wherein the step of increasing the bearing force by the incremental process force comprises increasing the pressure in the air cylinder by the incremental process pressure. . 66. The method of claim 57, further comprising the step of reducing the bearing force by an incremental step force. 67. The method of claim 66, wherein the step of reducing the bearing force by the incremental process force comprises reducing the pressure in the air cylinder by the incremental process pressure. .